Proposals submitted in response to a specific call issued by a sponsor. Such solicitations, typically called Request for Proposals (RFP), or Request for Quotations (RFQ), are usually have specific requirements for format and technical content, and may specify certain award terms and conditions. Broad Agency Announcements (BAAs) are not considered formal solicitations.
Proposals submitted to a sponsor that has not issued a specific solicitation but is believed by the investigator to have an interest in the subject.
These are requested by a sponsor who wants to minimize an applicant's effort in preparing a full proposal. Preproposals are usually in the form of a letter of intent or brief abstract. After the preproposal is reviewed, the sponsor notifies the investigator if a full proposal is warranted.
Continuation or non-competing proposals
These confirm the original proposal and funding requirements of a multi-year project which the sponsor has already provided funding for an initial period (normally one year). Continued support is usually dependent on satisfactory work progress and the availability of funds.
Renewal or competing proposals
Proposals which request continued support for an existing project that is about to end. These requests--from the sponsor's viewpoint--generally have the same status as an unsolicited proposal.